Ventilation system

ABSTRACT

A ventilation system for cleaning contaminated heated air generated by cooking appliances in a food preparation area, such as a kitchen, includes an inlet for contaminated heated air located in the food preparation area, a treatment part for cleaning the contaminated heated air, and an outlet for the cleaned heated air. The cleaned heated air is used as a heat source to heat the building in which the food preparation area is located.

The present invention relates to a ventilation system for use in a food preparation area such as a commercial kitchen, and more particularly to a ventilation system in which hot air from cooking appliances is treated and returned to the food preparation area or to another area of the building where the food preparation area is located.

A commercial kitchen (such as a kitchen in a restaurant) normally includes an electric (or gas) cooking line, with several cooking appliances (such as ovens, griddles, burners, fryers and the like). These heat the air, introduce cooking odours into the air, and, particularly in the case of fryers, contaminate it with smoke, droplets of oil and grease, and the like. This heated and contaminated air needs to be removed in order for the kitchen to remain an acceptable working environment. Similar issues arise with other food preparation areas, such as bakeries.

Removal of the heated and contaminated air is routinely carried out by means of purpose-made canopies or hoods above the appliances. These hoods are normally provided with grease filters, and are connected to accessible ducts, usually located above the hood and running through the ceiling space to a dedicated fan set, which is normally positioned on the roof of the building in which the kitchen is located. The fan is operated to discharge air from the ducts to the outside of the building, and this creates a lower pressure in the ducts which in turn helps evacuate the heated and contaminated air collected in the hoods.

However, the discharge of air from the ducts to the atmosphere outside the building can be undesirable. If cooking odours or contaminants are not removed before the air is discharged, the environment around the building can become unpleasant, and some local authorities in the United Kingdom refuse to allow new developments of food premises to discharge to the atmosphere.

A further problem with discharging the air to the atmosphere outside is that if all of the air sucked into the hoods were to be discharged in this way, this would result in a considerable fresh air make-up requirement to replace the discharged air. Further, heat in the discharged air is wasted, and the need to add heat to the make-up air in order to maintain a comfortable environment for the kitchen staff increases running costs. Normally, a small amount of the air (around 20 percent) is discharged, and the remainder is combined with make-up air/replacement air taken from the atmosphere, filtered, heated and returned to the kitchen; however, this still leads to wasted heat and increased running costs.

Furthermore, the need to provide ductwork to discharge air to atmosphere (and, if required, to bring make-up air in from the atmosphere outside the building) causes further problems. Often, the ducts will need to be located in risers, which imposes limitations on the possible layouts of the ductwork. Further, the ductwork in the riser will need to be made fireproof, increasing costs.

It is an object of at least the preferred embodiments of the invention to provide a ventilation system for food preparation areas such as kitchens that allows a more efficient use of the heat generated in cooking.

According to a first aspect of the present invention, there is provided a ventilation system for cleaning contaminated heated air generated by cooking appliances in a food preparation area such as a kitchen, comprising: an inlet for contaminated heated air located in the food preparation area; a treatment part for cleaning contaminated heated air; and an outlet for the heated air; wherein the heated air is used as a heat source to heat the building in which the food preparation area is located.

In the ventilation system of the invention, all of the heated contaminated air entering the inlet in the food preparation area is cleaned, and is retained in the building in which the food preparation area is located rather than being discharged to atmosphere. This avoids any problems associated with atmospheric discharge.

Further, as none of the air is discharged to atmosphere, none of the heat generated by the cooking appliances is lost, and all of it can be used to heat the building. This allows a more efficient use of the “waste” heat generated in cooking, and can significantly reduce heating costs for the building.

Furthermore, there is no need to supply any make-up air to replace discharged air, and so the ductwork which is normally required to supply make-up can be dispensed with, reducing installation costs. In addition, the energy which would have been required to heat the make-up air can be saved, thus reducing running costs.

The heated air can be used as a heat source in any suitable manner. In a simple arrangement, the outlet for the heated air is located in a region of the building which it is desired to heat.

In a preferred form, the outlet for the heated air is located in a dining area associated with the food preparation area, and the heated air is used to heat the dining area.

This can be particularly useful in “open-plan” dining areas, such as those found in shopping malls and the like. Heated air generated by a food preparation area can be discharged from the outlet into the dining area to heat it, and there can be multiple outlets for the heated air to provide a more uniform heating effect. Discharge can, in certain locations, take place at floor level.

At certain times of the year, the heated air returned to the space to be heated would be considered to be too hot, and would lead to discomfort. To avoid this, the treatment part may be provided with means for cooling the air. With such an arrangement, the temperature of the discharged air can be lower than the temperature of the air entering the inlet, to maintain acceptable comfort levels.

Any suitable means can be provided for cooling the air. In a preferred form, the hot air can be cooled in a direct exchange or chilled water cooling coil, connected to suitable heat injection equipment at roof level, before being discharged from the unit.

Air can be made to move through the treatment part in any suitable manner. However, in a preferred form, one or more fans are provided in the treatment part for creating a current of air from the inlet to the outlet.

The air can be cleaned in any suitable manner. However, it is preferred for the treatment part to clean the contaminated air by filtering it. Filtration is a well known method of cleaning air, and the filter or filters used can be tailored to the particular requirements of the installation.

Preferably, a series of filters are used. This allows better tailoring of the filtration to the requirements of the installation, rather than relying on a single filter.

As the filters will become clogged with removed contaminants after a prolonged period of use, they can be replaced after a certain period. However, it is preferred for the ventilation system to include a monitoring system which monitors the state of the filters.

With this arrangement, the installed life of the filters can be extended, as they will only be replaced when such replacement is actually necessary, rather than being replaced at specific times in accordance with a preset schedule.

Any suitable system for monitoring the state of the filters can be used. In a preferred form, the monitoring system includes transducers for measuring the pressure drop across the filters. As the filters become clogged, the pressure drop across them increases, and so the pressure drop across the filters allows the filter lifespan to be accurately determined.

In a preferred form, the monitoring system can control the speed of the fan depending on the state of the filters. For example, if the monitoring system has noted that a filter is becoming clogged with contaminants and will soon need to be replaced, the speed of the fan can be changed (for example, increased to maintain a predetermined air flow) until such time as the filter is replaced.

The monitoring system may be connected to a display panel on the treatment part, and can switch on lights (such as an amber or red light), to indicate that a filter should be or must be replaced.

In a preferred form, the monitoring system can send wireless alerts depending on the state of the filters. This allows a person in charge of maintenance of the system to be alerted to the need to change a filter, even if the person is not near the treatment part at the time.

It also preferred for the monitoring system to be accessible remotely. This allows a single maintenance operative to check on the state of the filters in several different installations from a single location, such as a central office.

In a preferred form, the treatment part also includes means for removing odours from the contaminated air. These can take any suitable form, but preferably include activated charcoal.

In a preferred form, the treatment part is located in a room separate from the food preparation area. By locating the treatment part in a room separate from the food preparation area, the amount of space required in the food preparation area itself can be reduced.

Further, maintenance of the treatment part may require the use of materials which should, ideally, be kept separate from food to prevent possible contamination of the food. Locating the treatment part in a room separated from the food preparation area allows maintenance to be carried out without the risk of such contamination, and without disturbing operations in the food preparation area.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a first embodiment of a ventilation system according to the present invention, used to ventilate a kitchen;

FIG. 2 shows a treatment part of the ventilation system, in which the air is filtered; and

FIG. 3 is a schematic view of a second embodiment of a ventilation system according to the present invention.

As shown in FIG. 1, the ventilation system 10 according to the first embodiment includes two main parts; an intake part 100, located in a kitchen 20 to be ventilated, and a treatment part 200, which in this case is located in a separate room 30. The treatment part 200 can also be located in the kitchen 20 to be ventilated, if necessary, but this is less desirable. The kitchen includes a number of cooking appliances 22 (shown schematically in FIG. 1).

FIG. 1 shows the treatment part 200 in a room 30 adjacent to the kitchen 20 to be ventilated (on the other side of a wall 40); the treatment part 200 does not need to be located adjacent to the kitchen 20, but such an arrangement reduces the ducting required to implement the system.

As shown in FIG. 2, the treatment part 200 of the ventilation system 10 includes a fan 210, which is operated to draw air through the treatment part from an inlet 220 to an outlet 230. FIG. 1 shows that the inlet 220 of the treatment part 200 is connected to ductwork 50 extending from the kitchen 20 through the wall 40 into the adjacent room 30, and this ductwork 50 in turn has one or more inlets 52 positioned above the cooking appliances 22, so that heated and contaminated air can be drawn into the ductwork 50 when the fan 210 is operated.

The outlet 230 of the treatment part 200 is connected to further ductwork 60 which extends away from the treatment part 200. All of the air entering the inlets 52 of the ductwork 50 above the cooking appliances 22 is drawn into the treatment part 200 by the fan 210, treated in the treatment part 200 (as will be described in detail later), and then passes through the further ductwork 60. This further ductwork can be connected to an outlet in an area in the building that requires heating, so that the cleaned heated air can heat that area. There is thus no need for a route to the outside of the building, as would be required with a conventional system.

Although the inlet 220 and outlet 230 of the treatment part are shown at different heights in FIG. 2, it will be appreciated that they can be at the same height (as in FIG. 3), depending on the particular requirements of the specific installation.

As mentioned in the introduction, the cooking appliances 22 heat the air, and introduce cooking odours and other contaminants. The heated and contaminated air is filtered in the treatment part 200 to remove contaminants and odours.

A series of filters 240 are located between the inlet 220 of the treatment part 200 and the fan 210. The first of these filters 242 serves to filter out heavy particulates from the incoming air (low grade grease filtration), the second 244 filters out light particulates (high grade grease filtration), and the third 246 filters out smoke. The third filter 246 may be a HEPA (high efficiency particle arrestor) filter.

Each of the filters 242, 244, 246 can be replaced independently of the other two. The first filter 242 will normally need to be replaced more frequently than the second filter, which in turn will need to be replaced more frequently than the third filter (for example, the first filter may need to replaced every month, the second filter may need to be replaced every three months, and the third filter may need to be replaced every six months.)

The first and second filters 242, 244 remove grease from the air which passes through them, and this grease will accumulate on the filters. If the design of the filter allows it, it may be possible to remove the accumulated grease and convert it into bio-fuel.

A monitoring system 250 (shown very schematically in the Figures) is provided to monitor the state of each filter 242, 244, 246, so that an alert can be sent to a user of the system when (or, more preferably, just before) each filter requires replacement. The system may use pressure transducers to determine the pressure drop across the filters, as this pressure drop will vary depending on the state of the filter.

The alerts can be sent wirelessly to a wireless device of the user (such as a smartphone or tablet), so that the user does not need to be permanently on-site. The alerts can also be sent to a central management site.

Monitoring dials or similar displays (such as a “traffic light” type system) can be provided on the treatment part, so that a local user can see the state of the filters. In addition, it is preferably possible for the monitoring system to be accessed online, ideally from a wireless device, so that the state of the filters can be monitored remotely in a “live” manner.

The monitoring system 250 can also be connected to the fan 210, and can vary the power of the fan depending on the state of the filters 240. For example, if the monitoring system notes that a filter is clogged with contaminants (such as grease) and needs to be replaced, the speed of the fan can be changed (for example, increased) until the filter has been replaced.

Further, the monitoring system 250 can be arranged to shut the system down in the event of a serious problem such as a total blockage of one or more of the filters 240. Sensors can be provided in the ductwork 60 which discharges air from the treatment part to monitor the quality and temperature of the cleaned air.

The monitoring system 250 can also include a fire detection system, which activates an independent fire extinguishing system if a fire is detected in the ventilation system 10.

Between the fan 210 and the outlet 230 of the treatment part 200 are located a series of activated charcoal filters 260. These are intended primarily to remove odours from the air. Again, the filters 260 can be replaced independently of each other, and of the filters 240. It is expected that the filters 260 will need to replaced annually.

In some situations, the charcoal filters may not be required. For example, if the ventilation system is used to remove heated and contaminated air from a bakery in a shopping mall, it may be desirable to retain the odour of baking bread in the discharged air.

Preferably, the treatment unit can only be opened (to allow access to the filters and fan) by an approved maintenance operative; this can be achieved simply by providing locks on the unit, and giving keys to the approved operative. Further, for safety reasons, it is preferred for the system to be arranged such that the fan cannot operate if the unit is open, or of one (or more) of the filters are not present.

FIG. 3 shows an alternative arrangement of a ventilation system, again used to extract heated contaminated air from a kitchen. Here, the system includes three main parts; an intake part (in the form of a kitchen extract canopy) 300, the treatment part 200, and a discharge part 320. The intake part 300 is located in a kitchen area, above the cooking appliances (which are not shown in FIG. 3). The treatment part 200 is located in a separate room, adjacent to the kitchen, and is connected to the kitchen extract canopy by kitchen extract ductwork (corresponding to ductwork 50 in FIG. 1).

The discharge part 320 is located in a dining area, which in this case is adjacent to the kitchen and the room housing the treatment part 200. It is connected to the treatment part 200 by supply ductwork (corresponding to ductwork 60 in FIG. 1).

FIG. 3 shows that the discharge part 320 includes several outlets 330 for the heated air. The number, size and location of the outlets can be varied depending on the heating requirements of the dining area. The outlets can be provided at floor level, or at high level, to blow heated air down in the space.

The supply ductwork can also extend into the kitchen, as shown in FIG. 3. If all of the air removed from the kitchen is discharged elsewhere (whether to atmosphere as in prior systems or to a dining area), this may lead to a strong air current through the building into the kitchen to replace the discharged air (unless steps are taken to introduce make-up air into the kitchen). Returning some of the cleaned air to the kitchen reduces this current (and reduces the need to introduce make-up air). As shown in FIG. 3, dampers 340 can be provided in the supply ductwork to allow the proportion of the heated air going to the dining area and the kitchen to be varied.

Sometimes (for example, during summer), it may not be desired to simply discharge the heated air into the dining area, as this may lead to the dining area becoming uncomfortably hot. Thus, it is preferred for the treatment part to be provided with means for cooling the air. This allows the temperature of the discharged air to be lower than the temperature of the air entering the inlet.

Preferred embodiments of the ventilation system have been described in the context of ventilation of a food preparation area, and specifically a kitchen. However, it will be appreciated that the system could be used to ventilate other rooms in which heated contaminated air is produced, such as workshops. The system could also be used in a domestic kitchen.

Further, it will be appreciated that arrangements of the ventilation system other than those shown in the Figures can be used. For example, the treatment part can be located in a ceiling void, or on the roof of the building, to make use of available but previously unused space. 

1. A ventilation system for cleaning contaminated heated air generated by cooking appliances in a food preparation area such as a kitchen, comprising: an inlet for contaminated heated air located in the food preparation area; a treatment part for cleaning contaminated heated air; and an outlet for the heated air; wherein the heated air is used as a heat source to heat the building in which the food preparation area is located.
 2. A ventilation system as claimed in claim 1, wherein the outlet for the heated air is located in a region of the building which it is desired to heat.
 3. A ventilation system as claimed in claim 2, wherein the outlet for the heated air is located in a dining area associated with the food preparation area, and the heated air is used to heat the dining area.
 4. A ventilation system as claimed in claim 1, wherein the treatment part is provided with means for cooling the air.
 5. A ventilation system as claimed in claim 1, with one or more fans in the treatment part for creating a current of air from the inlet to the outlet.
 6. A ventilation system as claimed in claim 1, wherein the treatment part cleans the contaminated air by filtering it.
 7. A ventilation system as claimed in claim 6, wherein a series of filters are used.
 8. A ventilation system as claimed in claim 7, wherein a monitoring system monitors the state of the filters.
 9. A ventilation system as claimed in claim 8, wherein the monitoring system includes transducers for measuring the pressure drop across the filters.
 10. A ventilation system as claimed in claim 8 further comprising a fan, wherein the monitoring system can control the speed of the fan depending on the state of the filters.
 11. A ventilation system as claimed in claim 8, wherein the monitoring system can send wireless alerts depending on the state of the filters.
 12. A ventilation system as claimed in claim 8, wherein the monitoring system can be accessed remotely.
 13. A ventilation system as claimed in claim 1, wherein the treatment part also includes means for removing odours from the contaminated air.
 14. A ventilation system as claimed in claim 13, wherein said means include activated charcoal.
 15. A ventilation system as claimed in claim 1, wherein the treatment part is located in a room separate from the food preparation area.
 16. (canceled) 